1. Field of the Invention
The present invention relates to a magnetic tape recording/reproducing device and a magnetic tape recording/reproducing system.
2. Description of the Related Art
FIG. 16 is a schematic drawing of a constitution of a conventional magnetic tape recording/reproducing device having a rotary head.
As shown in FIG. 16, the magnetic tape recording/reproducing device has a stationary drum 3, a rotary drum 3A installed thereon, and a magnetic head 2 mounted on the rotary drum 3A. On an outer peripheral surface of the stationary drum 3, a lead 4 for guiding running of the magnetic tape 1 is provided.
On an upstream side and a downstream side along the tape running direction across the rotary drum 3A, a pair of stationary guides 3B, 3C; a pair of first guide rollers 5, 6; and a pair of second guide rollers 7, 8 are respectively provided.
Each of the first guide rollers 5, 6 comprises a roller portion which rotates as being coupled with motion of the magnetic tape 1 which runs as being partially wound thereon, and unrotative flanges 9, 10 respectively provided on the top portions of the roller portions so as to restrict the upper edge of the magnetic tape 1.
Each of the second guide rollers 7, 8 comprises a roller portion which rotates as being coupled with motion of the magnetic tape 1 which runs as being partially wound thereon, and unrotative flanges 11, 12 provided on the bottom portions of the roller portions so as to restrict the lower edge of the magnetic tape 1.
The magnetic tape 1 runs while the upper edge thereof being restricted by the flanges 9, 10 of the first guide rollers 5, 6, the lower edge thereof being restricted by the flanges 11, 12 of the second guide rollers 7, 8, and the lower edge thereof also being guided by the lead 4 of the stationary drum 3. This allows the magnetic head 2 to trace correct tracks on the magnetic tape 1.
The restriction for the magnetic tape 1 by the first guide rollers 5, 6 and second guide rollers 7, 8 will be detailed below.
As shown in FIG. 17A, the first guide rollers 5, 6 are arranged so that the roller portions thereof are inclined slightly towards the upstream side away from the direction orthogonal to the running direction F of the magnetic tape 1. The magnetic tape 1 will have applied thereon force “A” along the spirally drifting direction effected through static friction force generated in relation with the outer peripheral surface of the roller portions, and position of the magnetic tape 1 can thus successfully be restricted while making the upper edge thereof contact with the flanges 9, 10 of the first guide rollers 5, 6.
Also as shown in FIG. 17B, the second guide rollers 7, 8 are arranged so that the roller portions thereof are inclined slightly towards the downstream side away from the direction orthogonal to the running direction F of the magnetic tape 1. The magnetic tape 1 will have applied thereon force “B” along the spirally drifting direction effected through static friction force generated in relation with the outer peripheral surface of the roller portions, and position of the magnetic tape 1 can thus successfully be restricted while making the lower edge thereof contact with the flanges 11, 12 of the second guide rollers 7, 8.
However in the conventional magnetic tape recording/reproducing device as described in the above, recording or reproduction in the reverse running direction of the magnetic tape 1 undesirably moves the magnetic tape 1 so as to separate the upper edge thereof in a direction departing from the flanges 9, 10 of the first guide rollers 5, 6 since the direction of the spirally drifting force exerted on the magnetic tape 1 will be inverted from the direction indicated by arrow “A” as shown in FIG. 17A.
Similarly, the direction of the spirally drifting force exerted on the magnetic tape 1 will be inverted from the direction indicated by arrow “B” as shown in FIG. 17B, which undesirably moves the magnetic tape 1 so as to separate the lower edge thereof in a direction departing from the flanges 11, 12 of the second guide rollers 7, 8.
This has been raising a problem that the magnetic tape 1 fluctuates up and down due to positioning failure of the upper and lower edges thereof, which adversely affects the tracking on the magnetic tape 1 to thereby degrade recording/reproduction characteristics to or from the magnetic tape 1.
The upper or lower edge of the magnetic tape 1 is pressed to the flange 9, 10, 11 or 12 during running of the magnetic tape 1 in the direction “F”, and the portion around the upper or lower edge is compressed as being affected by reaction force from the flanges.
As shown in FIG. 18A, when compressive force F2 exceeds maximum static friction force F1 expressed between the magnetic tape 1 and the outer peripheral surface of the roller potion, the magnetic tape 1 slips on the outer peripheral surface of the roller portion to be pushed back downward or upward, to thereby release the compressive force F2.
On the contrary as shown in FIG. 18B, when the compressive force F2 exceeds the buckling strength F3 of the magnetic tape 1 before the compressive force F2 exceeds the maximum static friction force F1 to thereby induce the sliding, the magnetic tape 1 buckles at the upper or lower edge portion to thereby cause damage. This undesirably narrows the tape width and causes flotation of the lower edge of the magnetic tape 1 from the lead 4 to thereby obstruct accurate and stable tracking.
The damaged magnetic tape 1 also deforms and rises at the edge thereof to thereby prevent itself from being brought into close contact with the rotary drum 3A, where a space generated between the magnetic tape 1 and magnetic head 2 is causative of output attenuation in the output.
Even if the buckling of the magnetic tape 1 should not occur, the upper edge or lower edge of the magnetic tape 1 can be damaged due to pressing to the flange 9, 10, 11 or 12, which may be causative of dropping of the magnetic powder, which will introduce drop-out (local omission of signals) or head clogging (signal attenuation caused by space generation due to adhered powder of worn tape onto the magnetic head).
Moreover, even if the upper edge or lower edge of the magnetic tape 1 should exempt from the damage, the edges may be compressed by being pressed to the flange 9, 10, 11 or 12 by an excessive force, which may degrade accuracy in the positional regulation of the magnetic tape 1 on the magnetic head 2, and may adversely affect the tracking on the magnetic tape 1.
These problems will become more distinct as the magnetic tape is further thinned with increase of recording density.